Process of producing metals.



UNITED STATES PATENT OFFICE.

SVEN EMIL sinuiuiv, or HoGANlis, SWEDEN.

PROCESS OF PRODUCING METALS.

No Drawing.

To all whom it may concern Be it known that I, SVEN EMIL SIEURIN,subject of the King of Sweden, residing at Hoganas, Sweden, haveinvented new and useful Improvements in Processes of Producing Metals,of which the following is a specification.

This invention has for its object the reduction of metals from theirores by means of coal which may without injury contain impuritiesinjurious to the metal, or coal rich in ashes, in solid form in such waythat no impurities, derived from the reducing material, are contained inthe metal produced.

In the production of iron and other metals it has heretofore beenproposed to heat an intimate mixture of powdered ore and re ducingagents without the access of air, or other gas from an external source,to such temperature that the metal is reduced without melting, and afterthe completion of the process and the cooling of the charge to separatethe fine particles of the metal from the impurities with which they aremingled by magnetic or other physical separating means.

Now according to the present invention no use is made of an intimatemixture of the ore with the reducing agent, but the ore is embedded in asolid reducing agent either in the form of lumps or briqucts or in theform of alternate layers, if the ore is in a powdered condition. At theend of the reducing process the einders and impurities resulting fromthe reducing agent may be separated from the lumps of reduced metalwithout difi iculty by physical means, because, as already mentioned,the ore and the reducing agent are not intimately mixed with oneanother. The metallic product obtained, consisting of lumps of reducedmetal, agglomerated with the rock of the ore, is thus purer than thatobtained by the reduction of an intimate mixture of pulverized ore andreducing agent and the method permits of the use of solid reducingagents of inferior quality, viz: those giving a large percentage ofashes.

In order to carry this invention into effect, ore, in the form of lumpsor briquets, roasted or not roasted, is mixed with a solid reducingmaterial, and charged into closed containers, whereby access of air isprevented, or if in a powdered state, is ar- Specification of LettersPatent.

Application filed May 6, 1910.

Patented June 24, 1913.

Serial No. 559,849.

ranged in such containers in alternate layers with said reducingmaterial, for instance in chambers with fire brick walls which areheated to such a temperature and for such a length of time thatreduction takesplace without the metal reduced being melted. Any methodof heating may be used which is adapted for the purpose. After cooling,the charge is removed from the chambers and the products of reductionare separated from the remainder of the reducing material in somesuitable way, for instance by dressing, screening, air separation orelectrostatic separation. If the reducing material in question iscontaminated with or contains sulfur, part of this sulfur would betransferred to the metal produced. This is prevent-ed by mixing thereducing material with compounds of calcium, such as carbonate, hydrate,or oxid. The carbonate or the like will then absorb almost all thesulfur and is afterward removed together with the remainder of thereducing material by suitable means. As is well known, lime or limestoneis much used as a sulfur-ab sorbing agent in metallurgical processes,but in all hitherto known processes the lime, containing the absorbedsulfur has been separated from the metal produced with the slag upon themelting of the metal, with the result that part of the sulfur enters themetal. By the present process a metal is obtained which is practicallyfree from sulfur. For instance, in the case of using reducing materialscontaining as much as one per cent. sulfur or more, it has been foundthat the sulfur in the metal recovered amounted to no more than .005 percent. The same result is accomplished by placing the lime or limestonebetween the ore and the reducing material or by a combination of bothmethods.

A suitable temperature for reducing iron ore is 1000 C. to 1300 C. andthe shortest time of heating with the usual dimensions of apparatus usedin practice with a good result has proved to be about four days. Theproportions of carbon and ore used are greatly variable and depend uponthe quality of the two materials as also on the temperature. In thereduction of very rich ore (70 per centaFe), however, a very good resulthas been obtained with 0.5 kg. of low grade carbon (giving 40 per cent.ashes) per 1 kg. ore. With the present process of recovering metals ithas proved very advantageous to expose the ore and the reducing means tothe influence of heat during a .uct more uniform and the remainder ofthe reducing material more easily removable from the reduction productafter the com pletion of the process, as compared with the conditionsprevailing when only a short time is allowed for the action of heat.Another advantage obtained in this way is that the metallic product willsinter together forming a denser product, more capable of resistingoxidation than otherwise would be the case. When carried out in this waythe process will also be more economical as a lower temperature andlarger charging chambers may be used than when the charge is exposed toheat for a shorter time. This increase in time consumed in the presentprocess compared with the time used according to older methods is veryconsiderable. In the blast furnace process a time not ex ceeding 15hours is usually used, whereas in the process in question several daysmay be required for the operation.

Coal, so rich in ashes as to be of no use in other processes may stillbe very suitable for use as a reducing agent in the present process, asthe ashes do not combine with the metal. Hitherto it has been impossiblewith advantage to use coal containing a large percentage of ashes forthe reduction of iron ore. Therefore this method offers great economicaladvantages, as coal rich in ashes is very cheap and so far has been inlittle demand.

It may be observed that the product ob tained does not consist of puremetal, but pieces or lumps of reduced metal, agglomerated with the rockof the ore, but free from the residue and ash of the reducing material.The resulting product moreover may be subjected to further treatment forinstance in Martin furnaces.

Having now particularly described and ascertained the nature of my saidinvention,

and in what manner the same is to be performed, I declare that what Iclaim is z- 1. In the reduction of iron ore, the process which comprisesassembling masses of such ore spaced by bodies of fuel, the size of suchmasses being such that the greater pro-portion of the material of suchmasses is out of contact with said fuel, and heating such assemblageunder exclusion of air to a temperature insuflicient to produce fusionbut suflicient to produce a reduction of such ore to the metallic state.

2. The method of producing a body of iron free from fuel contaminationswhich comprises assembling a substantial body of iron ore with one ormore faces in proximity to a body of fuel but with the greaterproport-ion of the ore in such ore body out of direct contact with saidfuel, heating the assemblage by externally derived heat to a temperaturebelow the melting point of iron until the ore is reduced, and thenremoving from the main metal body so produced the exterior facescontaminated by contact with solid materials from the body of fuel.

3. The method of reducing iron ore with low-grade sulfur-containing fuelwithout contamination of the produced iron by sulfur and other fuelimpurities which comp-rises admixing such fuel with sulfurretainingbases, assembling a body of such admixture in proximity to one or morefaces of a substantial body of ore, the greater proportion of thematerial in such admixture and of the ore in such ore body being out ofdirect contact, and heating the assemblage by externally derived heat toa temperature below the melting point of iron until the ore is reduced.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

SVEN EMIL SIEURIN.

\Vitnesses:

P. A. LINDAHL, GERMUND E. ANDERSON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, I). C.

